1966 started on a Saturday, and was not a leap year, so 21st October was a Friday.
October 2nd 1966 was on a Sunday.
29 October 1966 was a Saturday.
October 31, 1966 was a Monday.
6th October 1966 fell on a Tuesday.
Saturday
It was a Tuesday.
It was a Monday.
October 21st 1947 was a Tuesday.
21st October 1956 was a Sunday.
October 21st, 1991 fell on a Monday.
October 21st, 1998 fell on a Wednesday.
21st January 2004 fall on a Wednesday.